Practice round of ammunition



Oct. 30, 1962 J. s; DUNN 3,060,856

PRACTICE ROUND OF AMMUNITION Filed March 2, 1959 E m BY 0" i ATTORNEY 3,060,856 PRACTICE RGUND F AMMUNITIN .Ioseph S. Dunn, Clark riownship, Union County, NJ.,

assignor to Plastic Training Products Company, Bloomfield, NJ., a corporation of New `lersey Filed Mar. 2, 1959, Ser. No. 796,483 9 Claims. (Cl. 1in- 41) The present invention relates to ammunition and, more particularly, to a low-cost practice round of ammunition which is reusable without the use of complicated tooling or expensive recovery operations.

In the training of police and defense personnel to develop an adequate skill and proficiency in the ring of the weapons employed thereby and in the maintenance of such acquired proficiency initial and continued practice is essential. Heretofore the use of live ammunition for such instructional and practice sessions has been the only satisfactory answer to the problem. This use of live ammunition is necessary because heretofore practice rounds of ammunition were either inaccurate or provided no cost saving to the municipal, State or Federal agency using them. Due to the rising spiral or inflation this cost of live ammunition used for instruction and practice purposes for such municipal, state and federal agencies has become an increased burden to the taxpayer. As examples, the .45 caliber automatic, .38 caliber Special and .30 caliber Springfield O6 live rounds of ammunition cost 12, 9 and 21 each respectively.

In an attempt to reduce such instruction and practice costs, the cartridge cases of the fired live rounds of arnmunition are recovered, the primer being punched from the cartridge case by a special tool, and such cartridge case being recovered by machine operations to adapt such cartridge case for reuse. These machine operations comprise reaming the primer recess in the cartridge case to adapt such recess to receive a new primer and renecking or reducing the projectile aperture to receive a new projectile. This recovery procedure is expensive from the standpoint of the tools, machines and hand labor involved. In addition, the lead projectile of the live round ammunition is not reusable. Further the recovered cartridge case must be supplied with a new primer, powder and projectile before it is operable for use in a Weapon, thereby `further adding to the cost. The net result of the above-described recovery techniques, as applied to live rounds of ammunition, has resulted in no appreciable saving.

In the past many futile attempts have been made to achieve a practice round of ammunition, which is adapted for use in conventional iirearms, provides equivalent accuracy to a live round of ammunition, duplicates normal ring conditions, is low in cost and is reusable.

The earliest practice cartridge (of the type shown in U.S. Patent No. 517,719-, issued April 3, 1894, to G. D. R. Aikin) utilized a conventional projectile and modified the cartridge case by employing a shallow charge chamber disposed behind such projectile and communicating with the primer recess by means of a small bore. Such practice rounds are not reusable and have long since been eliminated from use. To render such practice round reusable the cartridge case was later provided with a cavity adjacent the primer recess and adapted to house a primer-catching device of the type shown in U.S. Patent No. 539,327, issued May 14, 1895, to G. D. R. Aikin. The resilient catches on the primer-catching device complicated its structure and became readily work hardened thereby defeating its purpose. In todays market its cost would be prohibitive.

Another earlier prototype of a practice cartridge (such as shown in U.S. Patent No. 531,233, issued December 3,968,355 Fatented Get. 30, 1962 icc 18, 1894, to W. M. Thomas) used a shorter lead bullet and compensated for such shorter lead bullet by providing asheet metal extension on the neck of the cartridge case. This type of practice was subject to all of the above-mentioned disabilities of alive round of ammunition, including high cost and lack of reusability.

Later, as shown in U.S. Patent No. 1,823,022, issued September l5, 1931, to F. Blechta, a hollow lead-core projectile having a transverse partition to protect the lead from the ilash and coated externally with copper was used to provide better trajectory stability and to prevent lead contamination of riiie bores. Manufacture of such a complicated projectile today would add to, not decrease, practice round expenses. In addition, the pojectile was not, of course, capable of being used again.

For cheapness of manufacture and short range use a hollow gilding-metal projectile of the type shown in U.S. Patent No. 1,892,158, issued December 27, 1932, to l. Matthews was suggested. A flared open mouth on the forward end of the bullet retarded the flight of the bullet and an enlarged rear portion thereon formed a rifle-barrel bearing. Under present day conditions lack of reuse, high cost and lack of accuracy have reduced such type of practice round to obscurity.

The practice cartridge shown in U.S. Patent No. 1,902,- 771, .issued lMarch 21, 1933, to A. F. Gardos comprised a blank cartridge inserted in the tip of the cartridge case for use as the propelling charge, the blank cartridge being tired by an auxiliary firing pin contained in the base of such cartridge case. The complex number of machined parts employed in this practice round of ammunition resulted in high costs, thus outweighting the desirable feature of ease of reloading.

Finally a practice round of ammunition of the type shown in U.S. Patent No. 2,812,713, issued November l2, 1957, to A. L, Fitzsimmons was introduced. The hollow cartridge case was shaped to simulate a conventional case and projectile and was adapted to contain a pellet. A detachable head housed a percussion cap and a solid cylindrical firing pin for exploding the cap charge through suitable ports extending to the pellet. 'This practice round cost about $1.50/round, Was reusable upon the addition of a new pellet and percussion cap but lacked the accuracy of the corresponding live round of ammunition.

It is the general object of the present invention to avoid and overcome the foregoing and other diiiculties of and objections to prior-art practice rounds of ammunition by the provision of an improved practice round of ammunition which is formulated from readily moldable matcrials and is low in cost.

Another object of the present invention is the provision of an improved practice round of ammunition, the essential components of which are reusable for about fifty shots without requiring extensive recovery operations or the use of special tools thereon.

Still another object of the present invention is the provision of an improved practice round of ammunition, the spent primer of which is readily removable by hand pressure on a simple hand tool, such as an awl or ice pick.

Yet another object of the present invention is the provision of an improved practice round of ammunition which may be reassembled by hand and a new primer added thereto with the aid of the back end of a simple hand tool.

A further object of the present invention is the provision of an improved practice round of ammunition which provides the equivalent accuracy of a similar live round of ammunition during its entire iiring life.

A still further object of the present invention is the provision of an improved practice round of ammunition which enables the user to practice in the use of a conventional irearm and provides a close duplication of normal iiringconditions so that such user is not affected by the transition to the use of live rounds of ammunition with such conventional firearm.

Another object of the present invention is the provision of improved practice rounds of ammunition for firearms of various calibers, which rounds utilize a universal primer thereby reducing the number of stock parts required for the various calibers and further simplifying the reloading operation.

, charge t'o the ash chamber with a minimized resistance to and loss of propelling force.

` The aforesaid objects of the present invention and other objects which will become apparent as the description proceeds are achieved by providing a practice round of ammunition having a hollow moldable cartridge case provided with a flash chamber and a primer-receiving aperture in one end of such ash chamber, a moldable projectile of relatively diiferent hardness than the cartridge case and having a shank portion of reduced diameter which is insertable by hand into the other end of the flash chamber in substantially hermetic engagement therewith and a primer insertable by the hand operation of a simple tool into the primer-receiving aperture in substantially hermetic engagement therewith and operable as the propellant for tiring the projectile from the cartridge case, the spent primer being manually removable from the cartridge case by insertion of the hand tool into the projectile-receiving end of the ash chamber to dislodge the Y used primer therefrom.

For a better understanding of the present invention reference should be had to the accompanying drawings,

wherein like numerals of reference indicate similar parts throughout the several views and wherein:

FIG. 1 is a perspective view of a .45 caliber practice round of ammunition of the present invention.

FIG. 2 is an enlarged exploded side-elevational view of the .45 caliber practice round shown in FIG. 1.

FIG. 3 is a fragmentary enlarged view of the lefthand portion of FIG. 2 and showing the details of the primer recess and guide portion.

FIG. 4 is a perspective view of a .38 caliber Special practice round of ammunition of the present invention.

FIG. 5 is a view similar to FIG. 2 but showing the .38 caliber Special practice round of FIG. 3.

FIG. 6 is a perspective view of a .30 caliber Springfield 06 practice round of ammunition of the present invention.

FIG. 7 is a View similar to FIGS. 2 and 4 but of the .30 caliber Springfield 06 practice round shown in FIG. 5.

Although the principles of the present invention are broadly applicable to any caliber of conventional ammunition, the present invention is particularly adapted for use in conjunction with the .45 caliber automatic, .38 caliber Specialand .30 caliber Springfield 06 type rounds of am` munition and hence it has been so illustrated and will be so described.

With speciiic reference to the form of the present inven- -tion illustrated in the drawings, and referring particularly to FIGS. 1 `and 2, a .45 caliber practice round of the ammunition of the present invention is indicated generally by the reference numeral 10.

This practice round of ammunition 10 has a cartridge case 12 formed of a moldable plastic having properties necessary to perform certain essential functions.

The moldable material of the cartridge cases 12 must be able to withstand the heat generated by the flash or propelling charge even under ambient outdoor temperatures of about F. Heat distortion temperature F.) at a liber stress of 264 p.s.i. lis the temperature required to permit an arbitrary standard amount of deflection by a standard load, under gradually increasing temperature and measures this heat-resistant property. In addition, such cartridge case 12 must be hard enough to withstand many chamberings in the rearm. 'I'his hardness property is measurable by the Rockwell test which expresses resistance to penetration by brief contact with a 1/2 spherical ball subjected -to a 10 kg. minor load and a 60 kg. major load. Further, a rim 19 of the cartridge case 12 must withstand the force of the firing pin striking the primer 30, which force would tend to shear off the rim 19 and the shock or impact of numerous extractor contacts which might dent or chip such rim 19. This impact strength is measured by the Izod test in ft.1b. per inch of notch and represents the energy required to break a notched test bar by means of a sharp blow, thus indicating the shockresistance of the moldable material.

The following table illustrates -the operating ranges of the cartridge case 12;

Properties: Range Heat distortion temperature, F 115 Hardness (Rockwell) 30-118 Impact strength ft.lb./inch of notch (1/2 X 1/2 in. notched bar., Izod test) 1.0-12.0

As an example, and not by way of limitation, such cartridge case12 may be made of a vinyl butarate plastic such as Butacite, the trade name of the product made by Du Pont de Nemours & Co., of Delaware, a polyethylene molding compound such as Alathon, the trade name of the product made by the Du Pont de Nemours & Co., of Delaware, or a nylon molding compound, such as Fiberiil, the trade name of the product made by the Fiberlil Corp., of Indiana.

While I am aware of the prior use of plastics, such as formaldehyde condensate, for a cartridge case as disclosed in U.S. Patent No. 2,083,665 issued June l5, 1937, to P. E. Pihl et al.; cellulose acetate for a cartridge case as taught in U.S. Patent No. 2,137,350, issued November 22, 1938 to H. A. Roberts; and polyethylene as taught by U.S. Patent No. 2,862,446, issued December 2, 1958, to L. Ringdal, such uses were confined to live rounds of ammunition and were not employed in practice rounds of ammunition to provide the structure and beneficial results of the present invention.

The cartridge case -12 is provided with a flash chamber 14, the right-hand end of which, as viewed in FIG. 2, serves yas a projectile-receiving aperture 16. The lefthand end of the cartridge case 12 is provided with a primer-recess 18 which extends inwardly from a featheredge rim 21 and terminates in a conical inwardly-tapering guide portion 20 leading -to a venturi aperture 22 which communicates with the left-hand end of the ilash chamber 14 by means of an outwardly-extending conical guide portion 24.

'I'his feather-edge rim 21 ('FIG. 3) desirably about .001 in thickness provides an entrance-lip diameter which is .0Q2-.003 less in diameter than the diameter of a primer 30, namely .210. The guide portion 20 (FIG. 3) is disposed at an angle 45) with the longitudinal axis of the cartridge case 12 and is essential for rapidly directing the propelling charge to the venturi portion 22 thereby preventing continement of such propelling charge or the creation of a rearward thrust on the iired primer 30, which thrust might dislodge the latter.

It will be understood that in orderVto adapt -the cartridge case 12 for use with a conventional .45 caliber lirearm, the length (.890"), rim diameter (.475) and diameter of the body (.470) of the cartridge case 12 are identical to the similar dimensions of the .45 caliber live round of ammunition. Y

For the purpose of adapting the right-hand end of the ash chamber 14, as viewed in FIGS. 1 `and 2, to receive a shank portion 26 of a projectile 28 in substantially hermetic engagement and thus prevent leakage of the ash or propelling charge there-between, such shank portion 26 has a diameter of `about .300 and the diameter of the ash chamber 14 is desirably .002-.003" smaller. The projectile 28 has a relative dierence in hardness from the cartridge case 12. By way of example, and not as la limitation, the projectile 28 being molded from a softer moldable material than the above described moldable material used in the cartridge case 12, such shank portion 26 is insertable by hand into the right-hand end of the ash chamber 14 in the less resilient cartridge case (without the use of tools) to accomplish the substantially hermetic joint. This insertion operation is similar in principle to the inserting of a resilient cork in the aperture of a glass bottle.

So that the primer 30, suitably -a Remington Large pistol primer No. 21/2 primer (having an outside diameter of about .210 and a length of about .l19) may be seated in the primer recess 18, such primer recess has a length of about .120" for seating the primer l30 inside the featheredge rim 21 at the entrance to the primer recess 18. Such primer 30 is started through the rim 21 in the primer recess 18 by hand and pushed into such primer recess by the ilat top of the wooden handle of an awl or ice pick (not shown) held in the hand of the loader. The rim 21 in cartridge case 12 (which is more resilient than the primer 30) permits the primer 30 to `snap fit into the primer recess 18 and causes the inner end of the primer 30 to seat against the tapered guide portion 20, thus locking the primer in place and forming a substantially hermetic seal between the primer 30 and the primer recess 18. This method of loading the primer is an improvement over the method shown in U.S. Patent No. 2,381,083, issued August 5, 1945, to I. S. Shulebottom, which patented method comprises heating the cartridge case of a live round of ammunition after insertion of the primer to secure the primer therein.

The moldable plastic projectile 28 is formed of a moldable material which is softer and more resilient than the plastic employed in the cartridge case 12.

The projectile must ybe hard enough to withstand the shock of tiring and the friction of movement through the barrel of the rearm, yet sufficiently soft to be grooved by the lands in the barrel, thus giving such projectile the proper spin which insures ystability and accuracy of the projectile in iiight. In addition, such projectile must have the necessary impact strength to withstand the impact incurred upon striking hard objects, such as a target, without losing its original shape. Further, the temperature of the propelling charge from the primer 30 must not deform the shank portion 26 of the projectile 28 so as to disturb -the substantially hermetic seal between such shank portion 26 and the projectile-receiving aperture 1'6 in the cartridge case 12.

The properties of a suitable moldable material for the projectile 28 are shown in the following table:

Properties: Range Heat distortion temperature, F 105 Hardness (Rockwell) 25-110 Impact strength ft.lb./inch of notch (1/2 x 1/2 in.

notched bar., -Izod test) 1.0-5.2

As an example, and not by Way of` limitation, such material may be `a polyethylene plastic such as Alathon, the trade name of the product of Du Pont de Nemours, of Delaware, or a cellulose acetate molding materials, such as plastacele, the trade name of the product of Du Pont de Nemours, of Delaware.

I am, of course, aware of the live-round projectile V'formed of lead, papier-mch and pulp shown in U.S.

Patent No. 355,653, issued January 4, 1887, to A. T. Loyd; the rtoy rubber projectile of U.S. Patent No. 2,539,968, issued January 30, 1951, to T. H. Payne; and the fragmenting projectile for live ammunition and formed of metal filler with a binder of ethyl cellulose disclosed in US. Patent No. 2,593,637, issued April 22, 1952, to L. C. Weldin. None of these projectiles are for use in a practice round of ammunition to provide the structure or results contemplated by the present invention.

When the firing pin of a conventional .45 caliber lirearm (not shown) strikes the primer 30, such primer 30 explodes and the resultant iash or propelling charge is guided by the tapered guide portion 20 to the venturi portion 22 (having a diameter of about .099) where the velocity of such propelling charge is increased, thus permitting such propelling charge to erupt (by means of the tapered guide portion 2.4) into the flash chamber 14 with attendant firing of `the projectile 28 from the barrel of the firearm (not shown) toward the practice target (not shown).

Assuming the shank portion 26 of the projectile has a length o-f about .187 projecting into the flash chamber, the length of the ash chamber 15 is about .750" and resultant volume ('ggy '750:.538 cu. in.

This volume V.45 for convenience of manufacture and simplicity of use, is held constant (for use with the No. 21/2 primer 30) in the .38 caliber Special practice round of ammunition 10a shown in FIGS. 4 and 5 and the .30 caliber Springfield '-06 practice round of ammunition 10b shown in FIGS. 6 and 7.

In order to render the projectile 28 (having a weight of about 20 grains as compared to 200 grains for lead projectile used in live rounds of ammunition) ballistically operative in conjunction with the propelling charge developed by the primer 30, the diameter (.450) of the body of the projectile 28- is the same as a conventional projectile but the length of such body is about .135 longer, thereby providing an overall length (l.400") in the practice round of ammunition 10 of the present invention as compared With a length (1265") of the conventional live round.

In order to reuse or recover the cartridge case 12 and projectile 28 of `the iired practice round of ammunition 10, the projectile 28 is recovered from the target area. The blunted end of the awl or ice pick (not shown) is inserted into projectile-receiving aperture 16 and through the ilash chamber 14, the venturi portion 22 and into contact with the red primer 30. Manual pressure on the handle of the awl or ice pick is suicient to dislodge the spent primer 30 from the rim 21 of the primer recess 18. A new primer 30 is then seated in the primer recess 18 as hereinbefore described, the projectile 28 is seated in the projectile-receiving aperture 16 by hand and the practice round of ammunition 10 of the present invention is ready for retiring.

As hereinbefore mentioned a conventional live round of .45 caliber ammunition costs about l2/round. The cartridge case 12 and projectile 28 of the above-described practice round of ammunition 10 cost about 3 and the primer 30 sells for .95, thus giving an initial cost per round of about Mt of the corresponding conventional live round. In addition, the practice round of ammunition 10 of the present invention is capable of being tired over fifty times at a cost of .95/refiring with no loss of accuracy over the conventional live round at Sty-50'.

Referring now to the .38 caliber Special practice round of ammunition 10a (FIGS. 4 and 5) and -to the .30 caliber Springeld 06 practice round of ammunition 10b (FIGS. 6 and 7) it will be noted that like numerals of reference with the suiiix "a and b appended thereto respectively indicate parts similar to the above-described similarly numbered lparts in FIGS. 1, 2 and 3. To permit universal use of the No. 21/2 primer 30 in the practice rounds of ammunition 10a and 10b and thus simplify procedures and reduce costs, the primer recesses 18a and 18b are While in accordance with the patent statutes one best known embodiment of the present invention has been illustrated and described in detail, it is to be particularly understood that the invention is not limited thereto or identical to the primer recess 18. Tapered guide portions thereby. 20a and 20b and 24a and 24b, as well as rims 21a and 2lb I claim: and venturi por-tions 22a and 22h have the same dimenl. A low-cost, reusable practice round of ammunition sions as the corresponding parts of the practice round of comprising a plastics tubular cartridge case having an ammunition shown in FIGS. l and 2. Since the pracend closure and an open end, said end closure being tice rounds of ammunition 10a and 10b are of smaller 10 provided with a prirner-receiving aperture, a plastics caliber, the ilash chambers 14a and 14b are longer but projectile projecting from said open end of the cartridge the volumes thereof V.38 and V3() are substantially equal case, said cartridge case being provided with a venturi to the volume V.45 (.538 cu. in.) of the flash chamber 14 portion between said primer-receiving aperture and said of the practice round of ammunition 10 (FIGS. 1 and 2). open end and spaced from said projectile, said projectile The following table gives a dimensional comparison in having a relatively lower hardness than said cartridge inches between the practice rounds of ammunition 10a case and being connected with said open end of the cartand 10b of the present invention and the corresponding ridge case, and a standard cartridge primer having an conventional live rounds: anvil in said primer-receiving aperture and operable as Over- Cart. Rim Diam. Diam Diam. Diam. Leu. of Len. ot all Case Diam. of Cart. oiNeck of of Shanlg Body Length Length ofCai-t. Case ofCart Body Shanlr oiProJ. olProj.

Case Case oProJ. ofProJ.

.38 cal. S eelal live round 1.505 1.125 .430 .380 .355 .38 Speel practice round 10a-.. 1.615 1.200 .430 .380 .240 .187 .415 .30 caLSprlngeldOGllveround- 3.250 2.480 .465 .465 .330 :305 .30 cal. Springfield 06 practice taper 303- round 10b 2.860 2.485 .465 465 .336 .305 -225 .187 .375

The above-noted dimensional variations between the the sole propelling charge for ring said projectile from practice rounds of ammunition 10a and 10b and the corsaid cartridge case, said venturi portion being operable responding conventional rounds are for the purpose of prorto rapidly increase the pressure behind said projectile viding projectiles 28a and 28h having essentially the same 35 Upon actuation of said primer. weight (namely 2() gl-ains) as the projectile 28, thereby 2. A low-cost, reusable practice round of ammunition .adapting Suh projectiles 23a and 2gb to respond unias set forth in claim l wherein said cartridge case has formly to the same propelling charge from the universal a Rockwell hardness in the range 0f abOut 30-118. primer 30 and the substantially uniform volumes (VAS, 3. A low-cost reusable practice round of ammunition vos and vso) of the sash chambers 14, 14a and 14h 40 as Set form in claim 1 wherein said projectile has a respectively. 'Ihe cartridge case 12a of the .38 caliber Rockwell hardness in the range Of about 25-110. Special practice round of ammunition 10a, FIGS. 4 and 5, 4' A 10W-cost reusable Practice found 0f ammunition is longer than the cartridge case of the corresponding live as Set form in claim 1 Wllefelll said cartridge case has round so that when the round 10a is loaded in the firea Rfckwell hardness in the fange 0f about 30-118 and arm (not shown) such case 12b rests against the centeran unpact stfeugtll 1Z0@ units in the range 0f abOllt ing slope of the cylinder chamber, thereby insuring the 10-12-0 and Sald Pfclcctlle has a ROCkWell hardness in sealing of the propelling charge and prevents the rim 19a the range .0f about 25-110 and au impact strength in of the cartridge case 12a from being ruptured by the force Izod umts 111 the fange 0f about .LO-52" of the ring pin striking the primer 30 and from forcing 5 A IOW'OS: reusable Practice found 0f ammuntiOn such rim 19a from the cartridge case 10a, thereby preas seit fom? m Clau- 1 wherein Said eud closure iS 3.150 venting case 10a from the being extracted and rendering 50 PfoVlied Wlth a fesll'leut feather-edge Ilm at the entrance case 10a unserviceable. to said-prmierreceiving aperture, and said primer is It will be recognized by those skilled in the art that locked 1n substantially hermetic engagement with said the objects of the present invention have been achieved pnmer'relvmg aperture by Saud f1mby providing an improved practice round of ammuni 6. A low-cost, .reusable practice round of ammunition tion which is formulated from readily moldable materials as seit forth nl dann 1 Whefejn Sad Prolectlle has a Shank and is low in cost. This improved practice round of pm uon of Shghtly large? dlameier ian Sad ope? end ammunition is reusable for as many as fty shots Withwhich shank Porilon 1s dlsposed m sald. open end m sub' out the necessity (after each ring thereof) of extensive stanuauy hermetic engagement .therewlth' recovery operations on its components or Without the 7 .low'cost rajusable Practl round of ammumtlon use of special toom In addition, the spent p rime 1 of 60 comprising a plastics tubular cartridge case having an such improved practice rounds of ammunition is readily end .closurq and al? open c nq Sad end qlosure being removable from the cartridge case by the application prqvlded-w1th .a pnmer'relvmg aperture. m. commi1m` of hand pressure on the simple hand tool, such as an atlon W1th-sald Open end a plasilcs molecule prolect' awl or ice Pick. The improved practice round of am- 6 m from iald op 6.11 end of lha carmdge. Czise arid a Siand munition may be reassembled by hand and a new primer 5 ar -carmdge Immer havmg an anvll m sald prmier' added thereto by pushing the primer into place with the rlcewmg apeiture .and operible as the? sole I TOPelllIlg handle end of the awl or ice pick. This improved pracc rge for rmg said molecule om said cartndge (.:zise tice round of ammunition provides the equivalent ac- .low'cost riusable pracuce @und of ammlimtlon curacy of the corresponding live round of ammunition, glpllg a pastlcs tubular cartlfldge case havmg .an and close duplication of normal tiring conditions with rean all open ein; said end closure bem? v I provided with a primer-receiving aperture in commumcclfespcudlug llVe Icuuds 0f aluuluultlcu s0 that che cation with said open end, a plastics projectile projecting lsoflonieol; tl tflijmsltlou from the Practice from said open end of the cartridge case, said projectile o e ive rounds of ammunition having a relatively lower hardness than said cartridge when using conventional firearms. case and being connected with said open end of the cartridge case, and a standard cartridge primer having an anvil in said primer-receiving aperture and operable as the sole propelling charge for ring said projectile from said cartridge case.

9. A low-cost, reusable practice round of ammunition comprising a plastics tubular cartridge case having an end closure and an open end, said end closure being provided with a primer-receiving aperture, a plastics projectile projecting from said open end of the cartridge case, said cartridge case being provided with a venturi portion between said primer-receiving aperture and said open end and spaced from said projectile, and a standard cartridge primer having an anvil in said primer- 10 receiving aperture and operable as the sole propelling charge for tiring said projectile from said cartridge case.

References Cited in the file of this patent UNITED STATES PATENTS 1,853,262 Dickerman Apr. 12, 1932 2,862,446 Ringdal Dec. 2. 1958 FOREIGN PATENTS 16,230 Great Britain of 1884 10,288 Great Britain of 1904 408,214 France Jan. 19, 1910 535,992 France Feb. 4, 1922 798,002 Great Britain July 9, 1958 

